Primary Analysis

On this page, we will take an in-depth look at the primary stage of the In Win Commander III 700 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.          

This power supply uses two rectifying bridges, which are attached to the same heatsink as the active PFC and switching transistors. The manufacturer, however, scratched the markings on the bridges, so we couldn’t identify them.

In Win Commander III 700wFigure 11: Rectifying bridges

The active PFC circuit uses two STW26NM60N MOSFETs, each one supporting up to 20 A at 25° C or 12.6 A at 100° C in continuous mode (note the difference temperature makes), or 80 A at 25° C in pulse mode. These transistors present a 165 mΩ maximum resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency. 

In Win Commander III 700wFigure 12: Active PFC diode and transistors

The output of the active PFC circuit is filtered by two 220 μF x 450 V Japanese electrolytic capacitors, from Panasonic, labeled at 105° C. They are the equivalent of a single 440 μF x 450 V capacitor.

In Win Commander III 700wFigure 13: Capacitors

In the switching section, another two STW26NM60N MOSFETs are employed using the traditional two-transistor forward configuration, which is interesting to see, since currently other manufacturers tend to use a resonant configuration for power supplies with the 80 Plus Gold certification. The specifications for these transistors were already discussed above.

In Win Commander III 700wFigure 14: The switching transistors

The primary is controlled by a CM6802 active PFC/PWM combo controller.

In Win Commander III 700wFigure 15: Active PFC/PWM controller

Let’s now take a look at the secondary of this power supply.

Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.